Kristin Cavallari's brother is causing her to worry

Kristin Cavallari's older brother, Michael, is missing, just days after she gave birth to her third child.

The Hills star Kristin Cavallari got awful news the day after Thanksgiving. Her older brother, Michael Cavallari, was reported missing after his car was found abandoned on a highway in Grand County, Utah.

The police investigated the area and used surveillance and credit card receipts from a convenience store in Monticello, Utah, to determine that Michael was the driver of the missing car. According to a press release from the Grand County sheriff's office, they are treating the disappearance as an active missing person's case.

This can't be an easy time for Cavallari, who just gave birth to her third child with husband Jay Cutler on Monday, Nov. 23. Daughter Saylor James joins older brothers Jax, 17 months, and Camden, 3.